Wireless sensors simplify installations

The Q45 SureCross sensors from Banner Engineering, Minneapolis, let engineers install sensors practically anywhere without the hassle of stringing cables for power or data. Sensor units will run for up to five years on two 3.6-V AA lithium batteries. The sensor comes in a sealed housing that carries an IP67/NEMA-6P rating. They provide a regular “heartbeat” signal to test connections. Loss of this signal alerts users as to which sensor is out.

There are four types of sensing units: retroflective, convergent, glass fiber, and remote device. The retroflective version emits a red beam of light. The sensor sends a signal when anything interrupts the beam. The convergent sensor detects small parts or profiles approaching from the side. The glass-fiber sensor fits in tight spaces and will withstand high levels of shock and vibration or corrosive materials and extreme moisture. The remote-device version works with dry contacts (pushbuttons), sourcing outputs, or Namur sensors.

The sensors send signals to a device called a Gateway. The board-mounted Gateway handles two sensors, while the QC Gateway handles up to six.

Users can also set up a multiple I/O network that handles up to 47 sensors. Sensors need to be within 3,000 ft of the Gateway with a clear line of sight.

In a typical plant with walls and obstructions, range is reduced to about 300 to 500 ft. Technicians can use the built-in signal-strength indicator to test specific applications. Signals are encrypted using pseudo-random signal hopping with cyclic redundancy checksum.